<?php
$undecided = 3.14;
echo "is ".$undecided." a double? ".is_double($undecided)."<br/>" ; // double

settype($undecided, 'string');
echo "is ".$undecided." a string? ".is_string($undecided)."<br/>" ; // string

settype($undecided, 'integer');
echo "is ".$undecided." an integer? ".is_integer($undecided)."<br/>" ; // integer

settype($undecided, 'double');
echo "is ".$undecided." a double? ".is_double($undecided)."<br/>" ; // double

settype($undecided, 'bool');
echo "is ".$undecided." a bool? ".is_bool($undecided)."<br/>" ; // double

?>